Tamperproof closure

ABSTRACT

A tamperproof closure adapted to be fitted on a container by a rotary motion of the closure, for example by means of threads, includes an inner cap having internal means for engaging the container, and an outer cap surrounding the inner cap. The outer cap has an aperture aligned with a projection extending from the end wall of the inner cap, so that the end walls of the caps are normally separated, but may be pushed together by forcing the projection through the aperture. When the caps are forced together suitable engaging means on the caps permit the caps to be rotated together. The projection is shaped to inhibit its withdrawal from the aperture once the caps have been forced together.

l TAMPERPROOF CLOSURE [75] Inventor: James A. McIntosh, Upper Montclair, NJ.

[73] Assignee: Mack-Wayne Plastic Company, Wayne, NJ.

[ Notice: The portion of the term of this patent subsequent to Sept. 4, 1990, has been disclaimed.

Filed: July 10, 1973 Appl. No.: 378,1 14

Related U.S. Application Data [63] Continuation of Ser. No. 246.968, April 24, 1972.

Pat. No. 3,756,444.

[52] U.S. Cl. 215/219 [51] Int. Cl. B65D 55/02 [58] Field of Search 215/218, 219, 220, 9, 7

[56] References Cited UNITED STATES PATENTS 3,756,444 9/1973 Mclntosh 215/9 Primary E.\'uminer-George T. Hall Attorney, Agent, or Firm-No1te and Nolte [57] ABSTRACT A tamperproof closure adapted to be fitted on a container by a rotary motion of the closure, for example by means of threads, includes an inner cap having in temal means for engaging the container, and an outer cap surrounding the inner cap. The outer cap has an aperture aligned with a projection extending from the end wall of the inner cap, so that the end walls of the caps are normally separated, but may be pushed to gether by forcing the projection through the aperture. When the caps are forced together suitable engaging means on the caps permit the caps to be rotated together. The projection is shaped to inhibit its withdrawal from the aperture once the caps have been forced together 10 Claims, 9 Drawing Figures US. Patent Nov. 11, 1975 TAMPERPROOF CLOSURE This is a continuation of application Ser. No. 246,968 filed Apr. 24, 1972, now US. Pat. No. 3,756,444.

This invention relates to closures for containers, such as bottles or the like, in which the closure is adapted to engage and be held on the container as a result of a relative rotary motion between the closure and the container. Conventionally, of course, such caps employ suitable threads for engaging threads on the container. The invention is specifically directed to the provision of a cap of this type which also includes an outer member surrounding the inner cap for inhibiting rotation of the inner cap, but being capable of manipulation to a position of mutual engagement so that the inner cap may be rotated by rotation of the outer member.

Closures of the above type have been employed in the past, and an example of such a closure is disclosed in my US. Pat. No. 3,520,435, which issued on July 14, 1970. As noted in the disclosure of my aforementioned patent, there are many products in daily use in modern households which may be harmful or dangerous when taken internally, so that conventional screw-on type of caps present a hazard in households where small children have access to the containers. It is of course no solution to this problem to advise people to place the containers in inaccessible locations. As a consequence, numerous forms of tamperproof closures have been suggested, as exemplified by my above mentioned patent.

Another problem also exists with respect to the provision of closures for containers, whether they be tamperproof or not. Containers of various materials, both harmful and nonharmful, and including some foodstuffs, are frequently openly displayed on the shelves of stores. Unfortunately, in view of the ready accessibility of these containers, it has been noted on some occasions that employees of the premises as well as customers occasionally open the containers for the purpose of sampling or use, and then return the partially emptied containers to the shelves. Subsequent purchasers of the partially emptied containers are frequently unaware of the tampering with the container they have purchased, and do not obtain the full value for their money. The possibility also arises that prior opening of the containers may result in the spoiling of the product.

In order to overcome this problem, it is further desirable to provide a closure which will provide a good indication to a purchaser of whether or not it has been tampered with. This problem can of course be overcome by the use of various seals, but many such tamperproof arrangements unnecessarily increase the expense in producing the closure member.

It is therefore the object of this invention to provide an inexpensive and easily manufactured tamperproof closure for a container, in which the operation of the closure by, for example, children, will be difficult, and in which the fact that the closure has been tampered with is normally readily visible.

Briefly stated, in accordance with my invention, I provide a tamperproof closure comprised of an inner cap and an outer cap. The inner cap has a top wall with a cylindrical skirt extending therefrom, the internal surface of the inner cap having a configuration, such as threads, permitting the inner cap to be firmly held on the neck surrounding an opening in a container. The outer cap also has a top wall and a cylindrical skirt extending therefrom. The outer cap is positioned so that its cylindrical skirt radially surrounds the cylindrical skirt of the inner cap, and means are provided for permitting limited relative axial movement between the inner and outer caps, while inhibiting total separation of the caps. In the preferred embodiment of the invention, the inhibiting means is in the form of an annular bead extending inwardly from. the bottom of the cylindrical skirt of the outer cap, to engage the bottom of the cylindrical skirt of the inner cap.

A projection is provided on the top wall of the inner cap and extending toward the outer cap, and an aperture is provided in the top wall of the outer cap aligned with the projection. The projection preferably has a round cross section, with its top of greater diameter than the diameter of the aperture, and its base diameter less than or equal to the diameter of the aperture. The projection thereby holds the two caps spaced apart, but the caps may be forced together so that the projection extends through the aperture. The inner and outer caps are provided with mutually engagable means, such as lugs, which are out of engagement to permit free rotation of the outer cap with respect to the inner cap when the top walls thereof are spaced apart by the projection, but which engage when the outer cap is forced downwardly onto the lower cap so that the projection extends through the aperture, thereby permitting rotation of the inner cap by manual rotation of the outer cap.

By providing an outer cap that is normally freely rotatable with respect to the inner cap, the closure device according to my invention inhibits opening of the closure device by persons not aware of the necessity for urging the projection through the aperture, such as small children. In addition, when the projection extends through the aperture, it is clearly evident that the closure has been tampered with. The projection is shaped so that its withdrawal from the aperture is inhibited once the caps have been forced together.

The invention will now be described in greater detail with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of a closure device according to the invention in place on the neck of a container;

FIG. 2 is a cross sectional view of a closure device according to a preferred embodiment of my invention, with the top walls of the inner and outer caps being separated by the projection to inhibit rotation of the inner cap, the cross section being parallel to the axis of the device;

FIG. 3 is a cross sectional view of a preferred embodiment of 'a closure according to the invention, differing from the view of FIG. 2 in that the projection in the top wall of the inner cap has been forced through the aperture in the top wall of the outer cap to permit rotation of the inner cap;

FIG. 4 is a cross sectional view taken along the lines 4-4 of FIG. 3, and illustrating the engagement between the engaging means of the inner and outer caps;

FIG. 5 is a cross sectional view of a portion of a modification of the closure of FIGS. 2 and 3;

FIG. 6 is a cross sectional view of a portion of another modification of the closure of FIGS. 2 and 3;

FIG. 7 is a cross sectional view of a portion of still another modification of the closure of FIGS. 2 and 3;

FIG. 8 is a cross sectional view of a further modification of a portion of the closure of FIGS. 2 and 3; and

FIG. 9 is a cross sectional view of a still further modification of a portion of the closure of FIGS. 2 and 3.

Referring now to the drawings, and more in particular to FIG. 1, therein is illustrated a closure device 10, according to the invention, in position on the neck of a typical container 11. As is apparent in FIG. 1, the only portions of the closure that are normally visible are an outer cap 12 having a top wall 13 with a central aperture 14, and a cylindrical skirt 15 extending downwardly from the top wall 13 around the neck of the container. The bottom of the aperture 14 is closed by the top 16 of a projection, which will described in more detail in the following paragraphs.

Referring now to FIG. 2, the closure according to the invention further comprises an inner cap 20 disposed within the outer cap 12, and coaxial therewith. The inner cap has a top wall 21 aligned with the top wall 13 of the outer cap, and a cylindrical skirt 22 extending from the top wall 21 and radially surrounded by the cylindrical skirt 15 of the outer cap. The inner cap 20 is provided with a configuration, such as threads 23 on the inside of the cylindrical skirt 22, to permit affixing of the inner cap to suitable configurations, such as threads, on the neck of the container 11 of FIG. 1. It will be understood, of course, that the form of the configuration for holding the inner cap onto the container does not form a part of the invention, and any configuration permitting the inner cap to be held on the container by virtue of at least a rotary movement is contemplated, since as will be apparent in the following paragraphs the closure is adapted to inhibit undesired rotary movement of the inner cap.

A centrally positioned projection 25 is provided on the top of the top wall 21 of the inner cap, and extending toward the top wall of the outer cap. The projection 25 preferably has a round cross section. The base 26 of the projection 25 has a diameter which is equal to or slightly less than the diameter of the aperture 14, while the top 16 of the projection 25 has a diameter greater than the diameter of the aperture 14. The projection 25 and aperture 14 are centrally disposed, i.e. along the axis of the closure, so that their alignment will be maintained with relative rotation of the outer and inner caps. For example, the projection may have an annular knob-like protrusion 27 at its uppermost portion. The projection 25 is intended to hold the top walls of the inner and outer caps in spaced apart positions as shown in FIG. 2, and if desired an annular recess 28 may be provided in the bottom of the aperture 14, against which the end 16 of the projection rests when the caps are in the spaced apart position.

It is of course desirable that the inner and outer caps be relatively unseparable while permitting a limited axial movement therebetween. For this purpose, an annular inwardly extending bead 30 is provided at the bottom of the cylindrical skirt 15 of the outer cap, the bead being positioned to engage the bottom of the cylindrical skirt 22 of the inner cap when the top walls of the caps are in their spaced apart position as illustrated in FIG. 3. The bead 30 thereby prevents the top walls of the caps from moving further apart, but permits their movement to a closer together position. The provision of the annular bead 30 is exemplary only, since such a configuration is easy to form in plastic members, and it will be understood that any conventional interengagemerit between the inner and outer caps which serves the above described function are contemplated herein.

While the top of the projection 16 is of larger diameter than the aperture 14, in accordance with the invention the outer cap 12 is made of a material which is sufficiently flexible and deformable to permit the projection 25 to be forced through the aperture 14 upon the application of pressure to the upper cap. For example, it is preferred that the outer cap be molded of a conventional plastic material, especially since such materials are readily formed to the other configurations of the cap. The requirements for materials of the inner cap are not as demanding with respect to resilience, although the inner cap is preferrably molded from a similar material. Thus, the materials employed for the inner cap and the outer cap may be made in accordance with the closure member disclosed in my above mentioned US. Pat. No. 3,520,435.

FIG. 3 illustrates the closure of FIG. 2 in which the outer cap has been forced downwardly so that the projection 25 extends therethrough. In this figure it is seen that the enlarged end 16 of the projection extends beyond the aperture 14, to inhibit movement of the outer cap back to its spaced apart position as illustrated in FIG. 2. The relative dimensions of the end 16 of the projection 25 and the aperture 14 are dependent upon the flexibility and deformability of the materials employed, and these dimensions should thus be selected so that the downward movement of the outer cap is accomplished only with some degree of difficulty. The recess 28 has been provided in order to permit a degree of freedom in the selection in the thickness of the top wall of the outer cap from the standpoints of strength and necessary flexibility, while still permitting a reduction in the overall longitudinal dimension of the closure. As illustrated in FIG. 3, when the outer cap has been forced down to the inner cap, the annular bead 30 is moved to a position spaced from the bottom of the skirt 22 of the inner cap.

The closure according to the invention is arranged so that the outer cap 12 is freely rotatable with respect to the inner cap 20 when the top walls of the two caps are held apart by the projection 25 in the position illustrated in FIG. 2, but that the inner cap and outer cap are rotatable together when the outer cap has been moved to the position illustrated in FIG. 3. For this purpose, according to one embodiment of the invention, as illustrated in FIGS. 2 and 3, inwardly extending ribs 35 are provided inside the cylindrical skirt 15 of the outer cap, and outwardly extending ribs 36 are provided on the outer surface of the cylindrical skirt 22 of the inner cap. A plurality of such ribs 35 and 36 may be provided around the circumference of the cylindrical skirts as illustrated in FIG. 4. The ribs 35 and 36 are positioned on their respective cylindrical skirts so that they are axially separated when the inner and outer caps are held apart as illustrated in FIG. 2, but are mutually engagable when the inner and outer caps are moved together as illustrated in FIG. 3. In the embodiment of my invention illustrated in FIGS. 2 and 3, the ribs 36 are adjacent the bottom of the skirt 22 of the inner cap, extending upwardly from an outwardly extending annular bead 37 at the bottom of the cylindrical skirt 22. The bottom of the cylindrical skirt 15 has a diameter, as illustrated at 38, to permit clearance of the ribs 36, while the upper portion 39 of the outer cap has a slightly reduced diameter to permit clearance with the upper portion of the cylindrical skirt of the inner cap. The ribs 35 are provided in the central region of the cylindrical skirt 15 between the portions 38 and 39 thereof. The ribs 35 and 36 are preferably relatively narrow in the circumferential direction, and are spaced apart, so that they do not inhibit movement of the outer cap to the position illustrated in FIG. 3. As an example, it has been found that from 5 to such ribs in each cap are adequate.

In the assembly of the closure according to my invention, it is preferred that the inner cap first be placed on the neck of the container and rotated to seal the neck of the container. Since the outer cap is of a flexible material, the outer cap may then be placed over the top of the inner cap, and the flexibility of the member will permit the walls of the outer cap to be flexed outwardly as the outer cap is forced downwardly until a position at which the annular bead 30 just snaps over the bottom of the cylindrical skirt 22. The outer cap should not be forced downwardly further than this, so that the projection 25 is never forced through the aperture 14 until the contents of the container are ready for use.

The closure of the invention may of course include sealing means, such as sealing rings integrally molded in the inner cap, if desired.

As illustrated in FIG. 3, inspection of a container incorporating a tamperproof cap according to the invention will readily reveal that the closure has been tampered with, since in this case the projection 25 will extend through the aperture 14 and be readily visible at the top of the closure.

In order to provide tamp erproof characteristics in the arrangement according to the invention, it is preferred that the components of the tamperproof cap be shaped to inhibit the removal of the projection 25 from the aperture once the outer cap has been forced downwardly. Thus, the top of the aperture 14 is as small as possible with respect to the diameter of the projection to provide a close fit, and the underside of the enlarged end 16 of the projection is formed as flat as possible, as determined by the molding techniques employed in the fabrication of the member, so that withdrawal of the projection from the aperture is as difficult as possible. In addition, withdrawal of the projection from the aperture is inhibited by the fact that when the outer cap is forced downwardly, the bottom of the outer cap is at its closest position to the container 1 1, so that it is difficult to get enough purchase on the bottom of the outer cap with the fingers to apply sufficient force on the outer cap to effect the removal of the projection from the aperture. Movement of the outer cap in the downward direction, however, is facilitated, for example, by providing a chamfer in the lower portion of the aperture, such as the annular recess 28, and by forming the top of the enlarged end 16 with as close to a full round surface as possible, at least in the portion thereof which engages the aperture. In addition, it is much easier to force the outer cap downwardly since there is ample surface on the top of the outer cap surrounding the aperture to enable the user to apply the necessary force thereto.

While as above stated it is preferred that the projection 25, and hence the aperture 14, have round cross sections, it is also contemplated that irregular cross sections may be permitted for the projection and aperture so that the irregular surfaces thereof can engage upon movement of the outer cap to the position illustrated in FIG. 3, and thereby permit rotation of the inner cap by virtue of the engagement of the aperture 14 and the projection 25. In such case the lugs or other similar en gaging means may of course be dispensed with if desired, and the diameters of the projection 25 and hence the aperture 14 should be increased to permit the application of the necessary rotary force to the inner cap.

Referring now to FIG. 5, therein is illustrated a modification of the closure of FIGS. 3 and 4 with respect to the ribs provided for mutual rotation of the inner and outer caps. In this arrangement, the inner cap is provided with spaced apart longitudinally extending ribs 40 of the same general form as illustrated in FIGS. 3 and 4, but extending upwardly toward the top wall of the inner cap for a greater distance, but not completely to the top of the inner cap. The outer cap as illustrated in FIG. 5 is of substantially equal diameter throughout its length, and internal ribs 41 are provided extending from the top wall 13 downwardly pass the top of the top wall of the inner cap but not so far as the ribs 40. When the inner and outer caps are spaced apart in the position illustrated in FIG. 5, the ribs 40 and 41 are axially separated, so that the outer cap can rotate freely, but the lower edges of the ribs 41 engage the upper edges of the ribs 40 when the outer cap is moved to its lowermost position, to permit mutual rotation of the inner and outer caps.

In the embodiment of the invention illustrated in FIG. 6, the ribs 43 on the outside of the inner cap ex tend throughout the length of the inner cap, while the longitudinal ribs 44 on the inside surface of the cylindrical skirt of the outer cap do not extend downwardly as far as the top of the inner cap when the inner and outer caps are in their separated position as illustrated in FIG. 6. When the outer cap is moved downwardly, the ribs 44 engage the ribs 43 to permit mutual rotation of the inner and outer caps.

In the further embodiment of FIG. 7, instead of providing ribs on the inner cap, the top of the inner cap may be provided with short longitudinally extending recesses 45, while the inside surface of the outer cap is provided with longitudinally extending ribs 46 adapted to engage the recesses 45 when the outer cap is moved downwardly (not shown), but be separated when the outer cap is held to its uppermost position by the projection 25.

In still another embodiment of the invention, as illustrated in FIG. 8, instead of providing the ribs as in the above examples of the invention, the bottom of the top wall 13 of the outer cap may be provided with downwardly extending projections 48 adapted to engage suitable recesses 49 in the top of the top wall of the inner cap when the outer cap is moved downwardly, but be separated therefrom when the outer cap is in its uppermost position as illustrated. The projections 48 and recesses 49 may have circular cross section, in which case their mutual alignment is required before fully moving the outer cap toward the inner cap. Alternatively, of course, the recesses may have triangular cross sections, with radially extending apices, the recesses being provided in a continuous configuration about the circumference of the top wall, with the projections 48 having a similar cross section, to obviate the necessity for close alignment of the inner and outer caps before moving the outer cap downwardly toward the inner cap.

In a still further embodiment of the invention, the inside surface of the outer cap may be provided with ribs 55 extending radially inwardly on the bottom of the top wall 13 from the cylindrical skirt, the top circumference of the top wall 21 being provided with radially inwardly extending ribs or recesses 56, so that the ribs or recesses 56 and the ribs 55 are mutually separated when the outer cap is held spaced apart from the inner cap by the projection 25, as illustrated, but mutually 7 engaged for common rotation of the inner and outer caps when the outer cap is moved downwardly toward the inner cap.

While the invention has been disclosed with reference to a limited number of embodiments, it will be obvious that many variations and modifications may be made therein without departing from the spirit and scope of the invention, and it is therefore intended that the invention as recited in the following claims cover all such variations and modifications as may be obvious from the above disclosure.

What is claimed is:

1. In a safety closure for a container of the type having a cylindrical neck over which a closure is adapted to fit and be held, the closure being of the type having an inner cap which is securable over the neck of the container by a rotary motion, and an outer cap surrounding the inner cap for selectively inhibiting rotation of the inner cap, and wherein engaging means are provided on the inner cap and outer cap for mutual engagement in a first relative axial position of the inner and outer caps, and be separated at a second relative axial position of the inner and outer caps; the improvement wherein said inner cap comprises a top wall and a cylindrical skirt extending downwardly therefrom for engagement with a container, and said outer cap has a top wall aligned with the top wall of said inner cap and having a cylindrical skirt extending therefrom and surrounding the cylindrical skirt of the inner cap, said inner cap further having a projection extending from the top wall thereof toward the top wall of said outer cap, said outer cap further having an axially extending aperture aligned with said projection, said projection having a base adjacent the top wall of said inner cap that is no greater than the diameter of said aperture, said projection further having a diameter at its end away from said top wall of said inner cap that is greater than the diameter of said aperture, whereby said projection holds said outer cap spaced from said inner cap in said second position and said projection may be forced through said aperture to attain said first position.

2. A tamperproof closure for a container of the type having a threaded neck, said closure comprising an inner cap having a first top wall and an internally threaded first cylindrical skirt extending therefrom for engaging the threaded neck of the container, said closure further comprising an outer cap having a second top wall and a second cylindrical skirt extending therefrom, said second skirt being positioned to surround said first skirt, a projection extending from said first top wall toward said second top wall, a aperture in said second top wall aligned with said projection, said projection having a base portion adjacent said first top wall of smaller cross sectional dimension than said aperture and an end portion of greater cross sectional dimension than said aperture, whereby said projection holds said second top wall in a first position spaced from said second top wall and said second top wall may be forced toward said first top wall with said projection extending through said aperture to a second position, and engaging means on said inner and outer caps positioned to permit free relative rotation of said inner and outer caps in said first position and to transmit rotary movement from said outer cap to said inner cap in said second position.

3. The tamperproof closure of claim 2 wherein said projection has a circular cross section and said aperture is round.

4. The tamperproof closure of claim 2 further comprising mutually engaging means on said inner and outer caps inhibiting separation of said inner and outer caps beyond said first position.

5. The tamperproof closure of claim 4 wherein said mutually engaging means comprises an annular inwardly extending head at the bottom of said second cylindrical skirt for engaging the bottom of said first cylindrical skirt.

6. The tamperproof closure of claim 2 wherein said engaging means comprises axially extending ribs on the outer circumference of said first cylindrical skirt, and axially extending ribs on the inner surface of said second cylindrical skirt.

7. The tamperproof closure of claim 6 wherein the ribs on said first cylindrical skirt extend outwardly from the bottom edge of said first cylindrical skirt, and the ribs on said second cylindrical skirt extend downwardly from said second top wall.

8. The tamperproof closure of claim 2 wherein said engaging means comprises radially extending ribs on the top of said first top wall and radially extending ribs on the bottom of said second top wall.

9. The tamperproof closure of claim 2 wherein said engaging means comprises projection means extending from said second top wall toward said first top wall, and recess means in said first top wall alignable with said projections in said second top wall.

10. The tamperproof closure of claim 2 wherein said second top wall further includes a recess surrounding said aperture on the side thereof toward said first wall, whereby said projection engages said recess in said first position. 

1. In a safety closure for a container of the type having a cylindrical neck over which a closure is adapted to fit and be held, the closure being of the type having an inner cap which is securable over the neck of the container by a rotary motion, and an outer cap surrounding the inner cap for selectively inhibiting rotation of the inner cap, and wherein engaging means are provided on the inner cap and outer cap for mutual engagement in a first relative axial position of the inner and outer caps, and be separated at a second relative axial position of the inner and outer caps; the improvement wherein said inner cap comprises a top wall and a cylindrical skirt extending downwardly therefrom for engagement with a container, and said outer cap has a top walL aligned with the top wall of said inner cap and having a cylindrical skirt extending therefrom and surrounding the cylindrical skirt of the inner cap, said inner cap further having a projection extending from the top wall thereof toward the top wall of said outer cap, said outer cap further having an axially extending aperture aligned with said projection, said projection having a base adjacent the top wall of said inner cap that is no greater than the diameter of said aperture, said projection further having a diameter at its end away from said top wall of said inner cap that is greater than the diameter of said aperture, whereby said projection holds said outer cap spaced from said inner cap in said second position and said projection may be forced through said aperture to attain said first position.
 2. A tamperproof closure for a container of the type having a threaded neck, said closure comprising an inner cap having a first top wall and an internally threaded first cylindrical skirt extending therefrom for engaging the threaded neck of the container, said closure further comprising an outer cap having a second top wall and a second cylindrical skirt extending therefrom, said second skirt being positioned to surround said first skirt, a projection extending from said first top wall toward said second top wall, a aperture in said second top wall aligned with said projection, said projection having a base portion adjacent said first top wall of smaller cross sectional dimension than said aperture and an end portion of greater cross sectional dimension than said aperture, whereby said projection holds said second top wall in a first position spaced from said second top wall and said second top wall may be forced toward said first top wall with said projection extending through said aperture to a second position, and engaging means on said inner and outer caps positioned to permit free relative rotation of said inner and outer caps in said first position and to transmit rotary movement from said outer cap to said inner cap in said second position.
 3. The tamperproof closure of claim 2 wherein said projection has a circular cross section and said aperture is round.
 4. The tamperproof closure of claim 2 further comprising mutually engaging means on said inner and outer caps inhibiting separation of said inner and outer caps beyond said first position.
 5. The tamperproof closure of claim 4 wherein said mutually engaging means comprises an annular inwardly extending bead at the bottom of said second cylindrical skirt for engaging the bottom of said first cylindrical skirt.
 6. The tamperproof closure of claim 2 wherein said engaging means comprises axially extending ribs on the outer circumference of said first cylindrical skirt, and axially extending ribs on the inner surface of said second cylindrical skirt.
 7. The tamperproof closure of claim 6 wherein the ribs on said first cylindrical skirt extend outwardly from the bottom edge of said first cylindrical skirt, and the ribs on said second cylindrical skirt extend downwardly from said second top wall.
 8. The tamperproof closure of claim 2 wherein said engaging means comprises radially extending ribs on the top of said first top wall and radially extending ribs on the bottom of said second top wall.
 9. The tamperproof closure of claim 2 wherein said engaging means comprises projection means extending from said second top wall toward said first top wall, and recess means in said first top wall alignable with said projections in said second top wall.
 10. The tamperproof closure of claim 2 wherein said second top wall further includes a recess surrounding said aperture on the side thereof toward said first wall, whereby said projection engages said recess in said first position. 